Changes in egg size have played a critical transitional role in the evolution of diverse groups of animals, but the relationship between the highly canalized process of development and the highly variable trait of egg size is not well understood. I will examine two facets of egg size variation using the model animal Drosophila melanogaster: (1) the genetics of egg size and (2) the developmental consequences of adaptive variation in egg size. One of the most well characterized regulatory cascades known is the expression of maternal effect patterning genes that define the anterioposterior axis in a Drosophila embryo. Paradoxically, questions remain concerning the precision and reproducibility of this diffusion-mediated process in embryos of varying size. I propose using both direct and indirect selection on egg size to resolve the relationship between scaling of the egg and the morphogenetic hypothesis for pattern formation in the Drosophila embryo. I will combine two questions. How are shifts in egg size developmentally coordinated with the morphogenetic gradients that establish positional information in a fly embryo? What QTL are segregating under different selection regimes? [unreadable] [unreadable] [unreadable]